This invention relates in general to chromatography and, more particularly, to an apparatus useful in the performance of thin layer chromatography of the type conducted in a plastic bag or the like.
Thin layer chromatography is an analytical chemical procedure conducted in numerous laboratories for determining the identity of compounds in a solution. Briefly, a solution containing a chemical compound to be identified is applied near one end of a chromatography sheet and the end of the sheet is immersed in an elution solvent which selectively separates the chemical compounds in the solution. Conventionally, thin layer chromatography of this type is conducted in thick glass tanks where the solvent is placed in the bottom of the tank, the chromatography sheet inserted into the tank and the tank covered with a glass sheet to provide a sealed chromatographic chamber. Although this type of device has proved useful in conducting thin layer chromatography, it is disadvantageous because the glass tanks are heavy, easily broken and expensive. Moreover, the use of these heavy, glass developing chambers are not particularly suitable for use in a portable thin layer chromatography system.
Thin layer chromatography has also been conducted in free-standing plastic sleeves. These sleeves are formed of a sturdy and semi-rigid plastic material and are closed at one end and open at the opposite end. The developing solution is inserted into the sleeve and the chromatographic sheet inserted into the solution. The sleeve is typically sealed by folding the top of the sleeve and attaching a clamp to the folded over portion of the sleeve. One disadvantage of this type of chromatographic chamber is that it is difficult to pre-equilibrate the atmosphere in the chamber before beginning the development of the chromatogram. A better and more accurate chromatogram is obtained if the atmosphere in the chamber is equilibrated with the vapors of the solvent before the chromatogram development is initiated. Moreover, the rigid plastic sleeves are expensive and not suitable for applications where numerous assays are being conducted.
A simple, portable, and inexpensive thin layer chromatography method using thin polyethylene bags as the developing chamber for developing the chromatogram has also been described. Because such bags can not stand on their own, a support apparatus is required to conduct chromatographic analysis in thin plastic bags. Heretofore, support assemblies developed for use in the performance of thin layer chromatography using thin polyethylene bags are cumbersome, inefficient, do not provide an adequate means for sealing the bag to provide an air tight developing chamber and require the use of supplemental sealing devices exterior of the support apparatus.
There is, therefore, a need for a facile, efficient and effective support apparatus for use in the performance of thin layer chromatography using thin plastic bags which overcomes the foregoing problems.